1. Field of the Invention
This invention relates to a material with viscoelasticity variable in electric fields, and more particularly, a polymeric material having variable viscoelasticity and suitable for use in making, for example, automobile parts adapted for the transmission or absorption of energy, or the isolation of vibration, such as clutches, dampers, shock absorbers, and engine mounts.
2. Description of the Related Art
Polymeric materials which can convert light, heat, electrical, or other energy into mechanical energy have recently come to be used for a wide variety of applications. In the automobile industry, too, there has been a demand for materials which can change their hardness, or viscoelasticity, as required, for making clutches, shock absorbers, engine mounts, and other automobile parts for the transmission or absorption of energy, or the isolation of vibration. The aforementioned polymeric materials have been expected to satisfy such a demand.
Known polymeric materials capable of converting electrical energy into mechanical energy are those which shrink (as disclosed in Japanese Laid-open Patent Publication No. 151824/1987), or bend, or bend and straighten (as disclosed in Japanese Laid-open Patent Publication No. 4731/1986), in response to an electric signal. These materials, however, consist of a polymer gel which is deformed by releasing a solvent from its solution subjected to electrical excitation, or by absorbing a solvent from an external source, thus causing volumeric change. None of these materials can, therefore, be used for making clutches, dampers, engine mounts, or any other automobile part that relies upon a change in hardness or viscoelasticity of the material for performing the transmission or absorption of energy, etc.